Internal vent for reducing seal pressure in prelubrication pump assembly

ABSTRACT

An engine prelubrication pump includes a pump housing with a pump cavity in which a first and second gear are positioned for pumping fluid. The first gear is operably and sealably connected to a motor for rotation and the second gear is rotatably mounted to a second shaft for geared rotation with the first gear. Fluid inlet and outlet ports are located in communication with the pump cavity and adapted respectively for connection with a source of fluid and a discharge means and an internal vent is positioned in between the armature shaft of bore and the pump housing along the inlet port. Alternatively, a valve is positioned between the inlet and outlet ports to selectively permit fluid pumped between the inlet and outlet ports to pass through when the outlet port is flow restricted.

CROSS REFERENCE

This application is a continuation in part application of U.S.application Ser. No. 08/896,779, filed on Jul. 18, 1997, entitled“Improved Pump Assembly.”

FIELD OF THE INVENTION

The present invention relates to an improved engine prelubrication pumpwhich operates with an internal combustion engine; and, in particular,to an oil pump which is driven by a starter motor armature drive shaftand which pump includes an internal vent for improved pump and motordurability. The invention is also applicable to stand alone orsupplemental prelubrication pumps.

BACKGROUND OF THE INVENTION

Generally, the fluid pump of the present invention is an improvementover pumps shown U.S. Pat. Nos. 4,553,512, 4,875,551 and 4,502,431.These pumps are used to lubricate the engine prior to the initial phaseof the cranking of the starter motor to turn over an engine. Typically,oil is used as a lubricant to allow engine parts to slide freely andeasily with reduced friction. Notwithstanding the use of lubricantshaving high lubricity there continues to be abrasive wear between metalparts in internal engine components such as the turbocharger, camshaft,crank shaft and rocker assembly, for example. It has been known for sometime that the greatest wear on internal engine parts is at thecommencement of ignition cranking and engine start-up. During that time,there is insufficient oil pressure in the engine to provide lubricationto the various parts throughout the engine. Accordingly, for theseinitial moments during start-up, there is metal rubbing against metalwithout a sufficient lubricant interface so that deterioration in theinternal engine components takes place over time.

A particularly important solution to this problem was provided by aprelubrication system disclosed in U.S. Pat. No. 4,502,431 in which oilis introduced in the engine prior to cranking and start-up. The startermotor is utilized as the means for powering the pump to provideprelubrication. In that system, the starter motor armature shaft isconnected to the pump's pumping gears which are rotated to provide thepumping action to the engine to prelubricate prior to the startermotor's solenoid engaging the starter to crank the engine for start-up.One particular embodiment of the starter motor and pump combination isdisclosed in U.S. Pat. No. 4,553,512 which is incorporated herein byreference.

The present invention provides a similar pump assembly as that disclosedin U.S. Pat. No. 4,553,512 to provide a selectable means for eitherprelubricating the engine or pumping the oil out for a quick efficientoil change. This is particularly useful to large fleet operators ofvehicles which require frequent oil changes.

Accordingly, it is an object of the present invention to provide a pumpmechanism to pump the oil out of an engine sump without having to openthe sump's oil plug. It is a further object of the invention to providea seal bore vent to the pump inlet to minimize the oil pressure at theseal during all modes of operation. It is a further object of theinvention to provide a prelube pump having a valve which is selectivelyoperable in the prelubrication mode as well as an oil exchange modeeither from the engine compartment and/or from a time delayed mechanism.

SUMMARY OF THE INVENTION

The present invention provides a gear-type pump which is integrated tothe starter motor of a vehicle. As disclosed in the aforementioned priorart, the base portion of the pump generally comprises the back orbearing end of the starter motor and includes a sealed opening throughwhich an extended armature shaft can be mounted to rotate or power thepump gears. A pump housing is integrally formed on the base plate whichprovides a cavity in which the pump gears are mounted and includes aninlet and outlet port. In addition, the present invention provides aseal bore vent to the pump inlet which uses a passageway from the pumpinlet into the armature shaft or pump seal bore to minimize the oilpressure at the seal during all modes of operation. This vent relievespressure from the seal which seals the pump cavity from the motorcavity. In this way, the pump and motor are further protected fromdamage and their longevity enhanced. This is especially the case when avalve selector and port are provided in the pump as set forth in one ofthe embodiments hereof.

Additionally, the invention may include an additional port for operationof valve mechanism to permit the oil to be pumped and bypassed to theoutlet port in normal operation. By rendering the valve “ineffective,”oil can be pumped to the outlet port for either prelubrication or forchanging the oil of the vehicle.

Other advantages of the present invention will become apparent from aperusal of the following description of a presently preferred embodimenttaken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of the pump of the present invention.

FIG. 2 is a side elevation of the pump shown in FIG. 1.

FIG. 3 is a sectional elevation of an embodiment of the presentinvention.

FIG. 4 provides a plan view diagram of a embodiment of the presentinvention showing oil flow path and pressure relief.

PRESENTLY PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2, pump 10 of the present invention comprisesbase plate 11 which is adapted to be bolted to the back portion of astarter motor (not shown) by means of a plurality of a circumferentiallypositioned bolts 12. Integrally formed in base plate 11 is pump housing13 having an elongated pump cavity 14 and central opening through whicha motor or armature shaft 16 extends therein. Cavity 14 also includesidler shaft 17 mounted fixably to the other portion of the cavity.Positioned within cavity 14 are pump gears 18 and 19 which are driven byarmature shaft 16.

Pump housing 13 also includes inlet port 21 and outlet port 22. Theseports are connected to inlet and outlet lines (not shown). Sealinglymounted to the pump housing 13 is sealing plate 23 which seals pumpcavity 14 from the outside and shaft seal 101 which seals pump cavity 14from the motor cavity, as shown in FIG. 3.

Pump housing 13 also includes a means to reduce pressure to the seal101. The means may include, for example, a vent area, channel or hole inthe pump or pump housing. In one embodiment, the means includes a vent50 from the pump seal bore 102 to the pump inlet 21 which provides apassageway or otherwise connects to and is positioned within pumphousing 13 on the side of inlet port 21, as shown in FIG. 4. In apreferred embodiment, the vent 50 is a grooved channel connecting witharmature shaft 16 or seal bore 102 of pump housing 13 and is positionedin the pump to relieve pressure from seal 101 to prevent damage to thepump and motor. In this way, vent 50 functions to minimize the oilpressure at the seal 101, as well as at seal bore 102, during all modesof operation. FIG. 4 also shows a diagram of an embodiment of thepresent invention of the oil flow path through channel 28 and pressurerelief through vent 50 and out suction port 21. In a preferredembodiment, vent 50 provides a self-adjusting restriction on increasesto the oil pressure. Vent 50 is also applicable to stand alone orsupplemental prelubrication pumps.

In a preferred embodiment sealing plate 23 includes housing 24. Inanother embodiment housing 24 also has a pair of bypass ports 26 and 27which are juxtaposed for communication between inlet and outlet ports 21and 22 respectively. A valve means, such as for example a selector valve30 comprised of a plug spring 31, and plunger or valvehead, ispositioned in channel 28 to provide selectable opening and closing ofthe channel. Valve means 30 is preferably a mechanically orhydraulically operated valve that is opened to permit recirculation.Alternatively, an electromechanical solenoid valve which is normallybiased in the open position can be used. When the valve 30 is open, oilrecirculates to the inlet port 21. In systems where rotation of thegears is normal operation oil flows through channel 28 as the pumprotates during starter motor initiation of conventional crank mode.Valve means 30 is shown having spring 31 which biases hydraulic valvemeans 30 closed. Oil pressure or electrical means 32 such as a solenoidopens valve 30 to permit the recirculation of oil through channel 28. Inan embodiment, vent 50 is useful to prevent any excess pressure in thepump seal bore 102 of a pump having restricted channel.

In the presently preferred embodiment, the valve means 30 will be closedwhen outlet port 22 is open to permit oil to be pumped therethrough.Outlet port 22 may include an oil line to the engine to provideprelubrication as well known in the prior art or to a dischargereceptacle, not shown, for changing the oil in the engine. A switchpositioned in the engine compartment can be used to simultaneouslyactivate the turning of the starter motor (without engaging the startersolenoid) so that the closed valve means 30 permits the oil to be pumpedout of the engine. Various other arrangements can be used to controlvalve means 30 with oil change and/or prelubrication flow control valves(not shown) positioned at the outlet port or line.

While presently preferred embodiments of the invention have been shownand described in particularity, the invention may be otherwise embodiedwithin the scope of the appended claims.

What is claimed is:
 1. An improved engine prelubrication pump assemblyfor use with a motor wherein the improvement comprises: a. a pumphousing having a pump cavity; b. a first and second gear positioned insaid cavity for pumping fluid, said first gear being operably andsealably connected to a motor shaft for rotation said shaft beingpositioned through a seal bore, and said second gear rotatably mountedto a second shaft for geared rotation with said first gear; c. fluidinlet and outlet ports in communication with said cavity and adapted forconnection with a source of fluid and a discharge means, respectively;d. a shaft seal which seals said pump cavity from said motor shaft; ande. an internal vent positioned between said shaft seal bore and saidinlet port, wherein said vent connects said bore to said inlet portthereby decreasing the pressure in the area of said seal.
 2. An improvedengine prelubrication pump assembly as set forth in claim 1 wherein saidfirst gear is operably connected to an independent motor.
 3. An improvedengine prelubrication pump assembly as set forth in claim 1 wherein saidmotor is a starter motor of a vehicle.
 4. An improved engineprelubrication pump assembly as set forth in claim 3 wherein an armatureof said starter motor comprises said means for rotating said first gear.5. An improved engine prelubrication pump assembly comprising a pumphousing having a pump cavity, two entrained gears positioned in saidcavity for pumping fluid and fluid inlet and outlet ports in combinationwith said cavity, said pump assembly further including a valve meanspositioned between said inlet and outlet ports, said valve means beingcontrollable to permit fluid pumped between the inlet and outlet portsto pass through said valve means when said outlet port is flowrestricted, said valve means being normally closed to fluid pumped bysaid first and second gears to flow from said inlet port to said outletport, during prelubrication or a fluid change, said valve means isopened to permit the oil to recirculate in response to a selectivecontrol input during operation of the pump when said prelubrication orfluid change is not selected.
 6. An improved engine prelubrication pumpassembly as set forth in claim 5 wherein said valve means is a hydraulicvalve biased closed until a preselected pressure is established by arestriction in oil flow to the outlet port.
 7. An improved engineprelubrication pump assembly as set forth in claim 5 further including avent positioned into said pump housing along said inlet port.
 8. Animproved engine prelubrication pump assembly as set forth in claim 7wherein said vent is connected to a motor shaft bore.
 9. An improvedengine prelubrication pump assembly as set forth in claim 5 furtherincluding a means to reduce the pressure in said pump assembly.
 10. In agear pump having a motor shaft positioned through a seal bore, fluidinlet and outlet ports in communication with a pump cavity and adaptedfor connection with a source of fluid and a discharge means, at leastone gear disposed in said pump cavity, and a shaft seal which seals saidpump cavity from said motor shaft, the improvement therein being a ventpositioned between said bore and said inlet port, wherein said ventconnects said bore to said inlet port thereby decreasing the pressure inthe area of said seal.